First: Is there anyone here who uses tumblr and benefits significantly from image/video descriptions? I've been making a small effort to champion them, but apart from the sorts of things that apply intermittently to everyone (A video blocked at your work or country, comics with tiny text etc) my arguments have all been about hypothetical users and it would be useful to (a)Have some evidence against the "but noone who needs descriptions would use a visual medium like tumblr" argument(*) and (b)Get any specific suggestions you guys might have to offer (like: given the fact that long descriptions are often cut off automatically or by rebloggers, is it better to do short ones? Or do you lose too much information?)

Second: With my fanart I've been pitching my descriptions at people who are familiar with canon unless I have some particular reason to think it will be interesting to those who aren't. In general I find writing descriptions quite mentally taxing and, beyond mentioning the names of the characters and canon so that people can google if they like, trying to imagine how to make the image make sense to someone who doesn't know canon without going into a three page backstory is usually too much for me. But since I don't really use image descriptions myself I worry I may be missing something. To give an example: Unless you're familiar with Homestuck, Redglare holds the chin of an angry looking Mindfang does not get across the fact that they are both grey skinned troll women with orange horns and specific outfits. But if you're not familiar with Homestuck, would you care?

(*)There are many good theoretical counterexamples to this, such as users who are there for the text posts or have issues with text at certain colours/sizes/fonts so are fine with pictures but not comics etc. Plus of course users who can see fine but can't hear videos etc. But proof that such tumblr users exist would be useful, if only so that people have to come up with a different excuse for not doing descriptions.